In this work the electrical properties of vapour detectors, formed from composites of conductive carbon-black and insulating organic multifunctional polymers having metal ions complexing ability, were investigated. The new composites are tailored to produce increased sensitivity towards specific classes of analyte vapours. Resonant frequency shift of a Quartz Crystal Microbalance (QCM) and DC resistance measurements have been also performed simultaneously on polymer-carbon black composite materials. For comparison purpose, poly(vinyl chloride) (PVC) with di(2- ethylhexyl)phthalate (DOP), a traditional low-molecular weight plasticiser, is used as representative of the behaviour of a traditional composite vapour detector. These new detectors showed an enhanced sensitivity upon exposure to acetic acid and amines vapours; the performances of our systems are 103 times higher than those of a traditional composite vapour detector. Moreover, the extent of such responses is beyond that expected by mass uptake upon exposure to the same vapours and can not be attributed solely to differences in polymer/gas partition coefficients. In this respect, several different chemical factors determine the DC electrical response of this system: in our opinion changes in polymer conformation during the adsorption process also play a significant role. The effects of the temperature on the electric resistance of the vapour detectors have been also studied. These materials showed a discontinuity in the temperature dependence of their resistance, and this discontinuity provided a simple method for determining the T-g of the composites.
PROPERTIES OF CARBON-BLACK COMPOSITE VAPOUR DETECTORS BASED ON MULTIFUNCTIONAL POLYMERS
SARTORE, Luciana;
2010-01-01
Abstract
In this work the electrical properties of vapour detectors, formed from composites of conductive carbon-black and insulating organic multifunctional polymers having metal ions complexing ability, were investigated. The new composites are tailored to produce increased sensitivity towards specific classes of analyte vapours. Resonant frequency shift of a Quartz Crystal Microbalance (QCM) and DC resistance measurements have been also performed simultaneously on polymer-carbon black composite materials. For comparison purpose, poly(vinyl chloride) (PVC) with di(2- ethylhexyl)phthalate (DOP), a traditional low-molecular weight plasticiser, is used as representative of the behaviour of a traditional composite vapour detector. These new detectors showed an enhanced sensitivity upon exposure to acetic acid and amines vapours; the performances of our systems are 103 times higher than those of a traditional composite vapour detector. Moreover, the extent of such responses is beyond that expected by mass uptake upon exposure to the same vapours and can not be attributed solely to differences in polymer/gas partition coefficients. In this respect, several different chemical factors determine the DC electrical response of this system: in our opinion changes in polymer conformation during the adsorption process also play a significant role. The effects of the temperature on the electric resistance of the vapour detectors have been also studied. These materials showed a discontinuity in the temperature dependence of their resistance, and this discontinuity provided a simple method for determining the T-g of the composites.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
